If you have something that outperforms SEO or PPC for generating sales, then you have something special on your hands.

SEO, Email Marketing, and Paid Search generally dominate online marketing as it relates to driving sales. This is true across most, but not all verticals. It is generally the case for eCommerce although social media can sometimes be more effective in certain categories.

Since this is well-known among eCommerce marketers, the best chance you have to validate your bold claim is to show bold results. Case Studies and testimonials will open the door for you. If ROI is 100% trackable, then this is the metric that you should focus on almost entirely.

From there, I'd suggest that you do two things:
1. Being a direct sales campaign focused on your target audience of ecommerce marketers.
2. Utilize your own platform to generate additional sales.

While you will likely not replace SEO or PPC, you could become a valuable addition to an eCommerce company's marketing mix.

Let me know if you're interested in discussing this further.